Clinical research involving children with cancer experiencing pain is centered in three areas: assessment and measurement, descriptive studies, and therapy. For clinical evaluation, 3 different modalities of pain measurement viz. a visual analogue scale, a verbal descriptor scale, and a picture face scale are being compared to evaluate their feasibility of administration and reliability in children of all ages experiencing acute or chronic pain. A cross-modality matching method for pain measurement is also being tested. Ongoing descriptive studies consist of (1) The prospective study of the predictive factors and nature of phantom limb pain and sensations in patients undergoing amputation and (2) The study of the prevalence and nature of pain in a childhood cancer population at initial presentation. Therapeutic studies: (1) A study of the efficacy and kinetics of fentanyl given by continuous intravenous infusion or transdermally in patients with malignancy who are experiencing pain is in progress; (2) A study of the use of nitrous oxide for children with malignancy undergoing painful procedures was recently closed, having shown good analgesic efficacy and safety, but high levels of occupational exposure to nitrous oxide; (3) Evaluation of topical agents, particularly ibuprofen, for pain control for chemotherapy-induced oral mucositis (in collaboration with NIDR) is in progress. Laboratory projects (in collaboration with NIMH) are assessing the role of various neuropeptides in the development of narcotic tolerance.